Parameters:
(1) extent of spleen below costal margin in cm
(2) erythroid precursors staining positive after immunostaining with Ret40f (antiglycophorin C) per square millimeter at x500 magnification in the hematopoietic (fat cell free) area of the trephine biopsy
(3) argyrophilic (reticulin and collagen) fiber density using the point-intersection method (number of intersections per square millimeter of hematopoietic area using an ocular grid, probably also at x500 magnification)
|
erythroid precursors
|
fiber density
|
spleen size below costal margin
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Risk Group
|
|
>= 360 per sq mm
|
< 32 intersections per sq mm
|
NA
|
low
|
|
>= 360 per sq mm
|
>= 32 intersections per square mm
|
NA
|
intermediate
|
|
< 360 per sq mm
|
NA
|
< 2 cm
|
intermediate
|
|
< 360 per sq mm
|
NA
|
>= 2 cm
|
high
|
from CART analysis shown in Figure 4, page 3002
|
Risk Group Treated With Interferon alfa-2b
|
Median Survival in Months
|
Relative Survival Rate at 5 Years
|
Odds Ratio for Blast Transformation Within 3 Years of Diagnosis
|
|
low
|
98
|
0.778
|
0.133
|
|
intermediate
|
57
|
0.497
|
0.313
|
|
high
|
43
|
0.404
|
0.900
|
from Tables 5 and 6, page 3004 (survival after busulfan, hydroxyurea or other therapy also given)
Limitations:
• Morphometric workstations are not widely available in routine practice.
• Morphometric examinations are time consuming and need to be verified for accuracy.
• It would be interesting to see if a semiquantitative method could be developed that could provide a similar risk stratification. Patients with reduced Ret40f+ erythroid precursors had greater anemia (page 2999).
